1. Molecules of Life Chapter 3

2. 3.1 Molecules of Life  Molecules of life are synthesized by living cells Carbohydrates Lipids Proteins Nucleic acids

3. Structure to Function  Molecules of life differ in three-dimensional structure and function Carbon backbone Attached functional groups  Structures give clues to how they function

4. Organic Compounds  Consist primarily of carbon and hydrogen atoms Carbon atoms bond covalently with up to four other atoms, often in long chains or rings  Functional groups attach to a carbon backbone Influence organic compound’s properties

5. An Organic Compound: Glucose  Four models

6. Functional Groups

7. Fig. 3.3, p. 36 In alcohols (e.g., sugars, amino acids); water soluble In fatty acid chains; insoluble in water In sugars, amino acids, nucleotides; water soluble. An aldehyde if at end of a carbon backbone; a ketone if attached to an interior carbon of backbone In amino acids, fatty acids, carbohydrates; water soluble. Highly polar; acts as an acid (releases H+) carboxyl methyl hydroxyl carbonyl (ionized)(non-ionized) (ketone)(aldehyde)

8. Fig. 3.3, p. 36 In amino acids and certain nucleotide bases; water soluble, acts as a weak base (accepts H+) In nucleotides (e.g., ATP), also in DNA, RNA, many proteins, phospholipids; water soluble, acidic amino phosphate icon (ionized)(non-ionized)

9. Functional Groups: The Importance of Position

10. one of the estrogens Fig. 3.4, p. 37 testosterone

11. Animation: Functional group CLICK HERE TO PLAY

12. Processes of Metabolism  Cells use energy to grow and maintain themselves  Enzyme-driven reactions build, rearrange, and split organic molecules

13. Building Organic Compounds  Cells form complex organic molecules Simple sugars → carbohydrates Fatty acids → lipids Amino acids → proteins Nucleotides → nucleic acids  Condensation combines monomers to form polymers

14. What Cells Do to Organic Compounds

15. Condensation and Hydrolysis

16. Fig. 3.5, p. 37 enzyme action at functional groups CondensationHydrolysis

17. Animation: Condensation and hydrolysis CLICK HERE TO PLAY

18. Key Concepts: STRUCTURE DICTATES FUNCTION  We define cells partly by their capacity to build complex carbohydrates and lipids, proteins, and nucleic acids  The main building blocks are simple sugars, fatty acids, amino acids, and nucleotides  These organic compounds have a backbone of carbon atoms with functional groups attached

19. 3.2 Carbohydrates – The Most Abundant Ones  Three main types of carbohydrates Monosaccharides (simple sugars) Oligosaccharides (short chains) Polysaccharides (complex carbohydrates)  Carbohydrate functions Instant energy sources Transportable or storable forms of energy Structural materials

20. Simple Sugars: Glucose and Fructose

21. Oligosaccharides: Sucrose

22. glucosefructose sucrose Fig. 3.6, p. 38 c Formation of a sucrose molecule

23. Complex Carbohydrates: Bonding Patterns

24. Complex Carbohydrates: Starch, Cellulose, and Glycogen

26. Fig. 3.8, p. 39 c Glycogen. In animals, this polysaccharide is a storage form for excess glucose. It is especially abundant in the liver and muscles of highly active animals, including fishes and people. Structure of cellulose

27. Animation: Structure of starch and cellulose CLICK HERE TO PLAY

28. Complex Carbohydrates: Chitin

29. Key Concepts: CARBOHYDRATES  Carbohydrates are the most abundant biological molecules  Simple sugars function as transportable forms of energy or as quick energy sources  Complex carbohydrates are structural materials or energy reservoirs

30. 3.3 Greasy, Oily – Must Be Lipids  Lipids Fats, phospholipids, waxes, and sterols Don’t dissolve in water Dissolve in nonpolar substances (other lipids)  Lipid functions Major sources of energy Structural materials Used in cell membranes

31. Fats  Lipids with one, two, or three fatty acid tails Saturated Unsaturated (cis and trans)  Triglycerides (neutral fats ) Three fatty acid tails Most abundant animal fat (body fat) Major energy reserves

32. Fatty Acids

33. Animation: Fatty acids CLICK HERE TO PLAY

34. Trans and Cis Fatty Acids

35. Triglyceride Formation

36. glycerol three fatty acid tails Triglyceride, a neutral fat Fig. 3.11, p. 40

37. Animation: Triglyceride formation CLICK HERE TO PLAY

38. Phospholipids  Main component of cell membranes Hydrophilic head, hydrophobic tails

39. hydrophilic head two hydrophilic tails Fig. 3.13, p. 41 b

40. c Cell membrane section

41. Animation: Phospholipid structure CLICK HERE TO PLAY

42. Waxes  Firm, pliable, water repelling, lubricating

43. Sterols: Cholesterol  Membrane components; precursors of other molecules (steroid hormones)

44. Animation: Cholesterol CLICK HERE TO PLAY

45. Key Concepts: LIPIDS  Complex lipids function as energy reservoirs, structural materials of cell membranes, signaling molecules, and waterproofing or lubricating substances

46. 3.4 Proteins – Diversity in Structure and Function  Proteins have many functions Structures Nutrition Enzymes Transportation Communication Defense

47. Protein Structure  Built from 20 kinds of amino acids

48. Fig. 3.15, p. 42

49. carboxyl group amino group

50. Fig. 3.15, p. 42

51. valine

52. Protein Synthesis

55. Four Levels of Protein Structure 1. Primary structure Amino acids joined by peptide bonds form a linear polypeptide chain 2. Secondary structure Polypeptide chains form sheets and coils 3. Tertiary structure Sheets and coils pack into functional domains

56. Four Levels of Protein Structure 4. Quaternary structure Many proteins (e.g. enzymes) consist of two or more chains  Other protein structures Glycoproteins Lipoproteins Fibrous proteins

57. Levels of Protein Structure

58. Fig. 3.17, p. 43 a Protein primary structure: Amino acids bonded in a polypeptide chain.

59. Levels of Protein Structure

60. Fig. 3.17, p. 43 b Protein secondary structure: A coiled (helical) or sheetlike array, held in place by hydrogen bonds ( dotted lines) between different parts of the polypeptide chain. helical coilsheet

61. Levels of Protein Structure

62. Fig. 3.17, p. 43 c Protein tertiary structure: A chain’s coiled parts, sheetlike arrays, or both have folded and twisted into stable, functional domains, including clusters, pockets, and barrels. barrel

63. Levels of Protein Structure

64. Fig. 3.17, p. 43 d Protein quaternary structure: Many weak interactions hold two or more polypeptide chains together as a single molecule.

65. Animation: Structure of an amino acid CLICK HERE TO PLAY

66. Animation: Peptide bond formation CLICK HERE TO PLAY

67. Animation: Secondary and tertiary structure CLICK HERE TO PLAY

68. Animation: Globin and hemoglobin structure CLICK HERE TO PLAY

69. 3.5 Why is Protein Structure So Important?  Protein structure dictates function  Sometimes a mutation in DNA results in an amino acid substitution that alters a protein’s structure and compromises its function Example: Hemoglobin and sickle-cell anemia

70. Normal Hemoglobin Structure

71. Fig. 3.18, p. 44 alpha globin heme a Globin. The secondary structure of this polypeptide includes several helixes. The coils fold up to form a pocket that cradles heme, a functional group with an iron atom at its center. The kind of molecular representation shown here is called a ribbon model, after its appearance. Appendix V has more details about such models.

72. Normal Hemoglobin Structure

73. alpha globin beta globin Fig. 3.18, p. 44 alpha globin b Hemoglobin is one of the proteins with quaternary structure. It consists of four globin molecules held together by hydrogen bonds. To help you distinguish among them, the two alpha globin chains are shown here in green, and the two beta globins are in brown.

74. Sickle-Cell Mutation

75. Fig. 3.19, p. 45 THREONINE VALINEHISTIDINELEUCINE GLUTAMATEPROLINEGLUTAMATE a Normal amino acid sequence at the start of a beta chain for hemoglobin.

76. Sickle-Cell Mutation

77. Fig. 3.19, p. 45 VALINEHISTIDINELEUCINEGLUTAMATEVALINETHREONINEPROLINE sickle cell normal cell b One amino acid substitution results in the abnormal beta chain in HbS molecules. Instead of glutamate, valine was added at the sixth position of the polypeptide chain. c Glutamate has an overall negative charge; valine has no net charge. At low oxygen levels, this difference gives rise to a water-repellent, sticky patch on HbS molecules. They stick together because of that patch, forming rodshaped clumps that distort normally rounded red blood cells into sickle shapes. (A sickle is a farm tool that has a crescent-shaped blade.)

78. Sickle-Cell Mutation

79. Clumping of cells in bloodstream Circulatory problems, damage to brain, lungs, heart, skeletal muscles, gut, and kidneys Heart failure, paralysis, pneumonia, rheumatism, gut pain, kidney failure Spleen concentrates sickle cells Spleen enlargement Immune system compromised Rapid destruction of sickle cells Anemia, causing weakness,fatigue, impaired development,heart chamber dilation Impaired brain function, heart failure Fig. 3.19, p. 45 d Melba Moore, celebrity spokes- person for sickle-cell anemia organizations. Right, range of symptoms for a person with two mutated genes for hemoglobin’s beta chain.

80. Clumping of cells in bloodstream Spleen concentrates sickle cells Rapid destruction of sickle cells Circulatory problems, damage to brain, lungs, heart, skeletal muscles, gut, and kidneys Heart failure, paralysis, pneumonia, rheumatism, gut pain, kidney failure Spleen enlargement Immune system compromised Anemia, causing weakness,fatigue, impaired development,heart chamber dilation Impaired brain function, heart failure Fig. 3-19, p. 45 d Melba Moore, celebrity spokes- person for sickle-cell anemia organizations. Right, range of symptoms for a person with two mutated genes for hemoglobin’s beta chain. Stepped Art

81. Animation: Sickle-cell anemia CLICK HERE TO PLAY

82. Denatured Proteins  If a protein unfolds and loses its three- dimensional shape (denatures), it also loses its function  Caused by shifts in pH or temperature, or exposure to detergent or salts Disrupts hydrogen bonds and other molecular interactions responsible for protein’s shape

83. Key Concepts: PROTEINS  Structurally and functionally, proteins are the most diverse molecules of life  They include enzymes, structural materials, signaling molecules, and transporters

84. Animation: Molecular models of the protein hemoglobin CLICK HERE TO PLAY

85. 3.6 Nucleotides, DNA, and RNAs Nucleotide structure, 3 parts: Sugar Phosphate group Nitrogen-containing base

86. Fig. 3.20, p. 46 three phosphate groups base (blue) sugar (orange)

87. Nucleotide Functions: Reproduction, Metabolism, and Survival  DNA and RNAs are nucleic acids, each composed of four kinds of nucleotide subunits  ATP energizes many kinds of molecules by phosphate-group transfers  Other nucleotides function as coenzymes or as chemical messengers

88. Nucleotides of DNA

89. Fig. 3.21, p. 46 adenine (A) base with a double-ring structure phosphate group sugar (deoxyribose)

90. Fig. 3.21, p. 46 THYMINE (T) base with a single-ring structure

91. Fig. 3.21, p. 46 GUANINE (C) base with a double-ring structure

92. Fig. 3.21, p. 46 CYTOSINE (C) base with a single-ring structure

93. DNA, RNAs, and Protein Synthesis  DNA (double-stranded) Encodes information about the primary structure of all cell proteins in its nucleotide sequence  RNA molecules (usually single stranded) Different kinds interact with DNA and one another during protein synthesis

94. The DNA Double-Helix

95. Fig. 3.22, p. 47 covalent bonding in carbon backbone hydrogen bonding between bases

96. Key Concepts: NUCLEOTIDES AND NUCLEIC ACIDS  Nucleotides have major metabolic roles and are building blocks of nucleic acids  Two kinds of nucleic acids, DNA and RNA, interact as the cell’s system of storing, retrieving, and translating information about building proteins

97. Animation: Nucleotide subunits of DNA CLICK HERE TO PLAY

98. Animation: Structure of ATP CLICK HERE TO PLAY